-LRB- CNN -RRB- -- A major investor in convicted swindler Bernie Madoff 's Ponzi scheme drowned in his swimming pool in Florida after a heart attack , his attorney said Monday . The medical examiner 's office confirmed the report .

Jeffry Picower , 67 , was found unconscious in his pool shortly after noon Sunday at his Palm Beach , Florida , , home by his wife , Palm Beach police said . He was pronounced dead at Good Samaritan Hospital .

Picower 's attorney , William Zabel , told CNN that Picower drowned after suffering a massive heart attack . Sue Jaffe , spokeswoman for the Palm Beach County medical examiner , confirmed those details .

In September , Forbes magazine ranked Picower No. 371 among the 400 richest Americans , with a net worth of $ 1 billion .

In March , Madoff was convicted of operating a Ponzi scheme and defrauding thousands of investors . He was sentenced to 150 years in prison after pleading guilty to 11 felony counts of fraud , money laundering and perjury . Prosecutors have said it was the largest investor fraud ever committed by a single person , totaling billions in losses to investors .

When the Picower Foundation of Palm Beach announced it was shutting down early this year because of Madoff losses , it initially appeared that the prominent philanthropist had been an unfortunate victim of Madoff 's Ponzi scheme . Picower 's 2007 tax return had valued his foundation 's portfolio at $ 955 million .

However , in May , court filings by Madoff trustee Irving Picard changed the picture . The trustee 's complaint claimed that Picower had been a key beneficiary of Madoff 's Ponzi scheme for more than 20 years , and `` knew or should have known that -LSB- he -RSB- was profiting from fraud because of the implausibly high rates of return '' on his accounts .

Those `` anomalous and astronomical rates of return '' -- as high as 500 percent in one year and 950 percent in another year -- `` were neither credible nor consistent with legitimate trading activity , and should have caused any reasonable investor ... to inquire further , '' the court filings said , referring to Picower as `` a sophisticated investor , accountant and lawyer . ''

Citing backdated account filings and other bogus paperwork , the complaint contends that `` Picower and the other defendants also knew or should have known that they were reaping the benefits of manipulated purported returns , false documents and fictitious profit . ''

The Picowers recently told The New York Times that the publicity and controversy surrounding their connection to Bernie Madoff had been a great source of heartache .

`` We always have been private people , and having all this play out in the media has taken a big toll on our health , '' the couple wrote in response to questions posed by reporters .

`` We feel stunned , betrayed , angry , sickened , devastated , '' they said , and were only able to draw strength and consolation `` from each other and from the knowledge that we did nothing wrong . ''

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Jeffry Picower , 67 , found unconscious in his pool in his Palm Beach , Florida

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Picower drowned after having a heart attack , his attorney and medical examiner say

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Picower had invested with Bernie Madoff , who was convicted in Ponzi scheme

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Forbes magazine ranked Picower No. 371 among the 400 richest Americans